Help for decimal conversion
Hi everybody.
I’m trying to make a differential thermostat for a solar water heating system using a 16f876 and two DS1820. I succeeded using as a starting point the onewire.bas in the examples. The sensors are used on two different pins. The temperature difference at which the pump has to start was initially fixed at 7°C with no problems but now I’d like to make it selectable between say 7 and 20 degs.
I have tried this program and it works, except that I can evaluate the set temperature difference only
memorizing the strange symbols displayed or their sequence. Can anybody help me solving this conversion problem? Any other suggestion will be very much appreciated.
' Differential thermostat
temperature VAR WORD ' Temperature storage
count_remain VAR BYTE ' Count remaining
count_per_c VAR BYTE ' Count per degree C
temperapanel VAR WORD ' Panel temperature storage
count_rempan VAR BYTE
count_per_cpan VAR BYTE
DQ VAR PORTA.4 ' One-wire data pin for boiler
DP VAR PORTA.5 ' One-wire data pin for panel*
delta VAR WORD ' Delta T° btwn Panel & Boiler to start pump
' Define LCD registers and bits
DEFINE LCD_DREG PORTB
DEFINE LCD_DBIT 4
DEFINE LCD_RSREG PORTA
DEFINE LCD_RSBIT 2
DEFINE LCD_EREG PORTA
DEFINE LCD_EBIT 1
DEFINE LCD_BITS 4
DEFINE LCD_LINES 2
DEFINE LCD_COMMANDUS 2000
DEFINE LCD_DATAUS 50
ADCON1 = 7 ' Set PORTA and PORTE to digital
LCDOut $fe, 1, "Diff. Thermostat"
Pause 3000
delta = 700 ' DEFAULT T° DIFFERENCE AT WHICH PUMP STARTS
mainloop: IF PORTA.3 = 0 Then pressed ' CHECK IF TEMPERATURE DIFFERENCE
' BUTTON IS PRESSED
OWOut DQ, 1, [$CC, $44] ' Start temperature conversion
waitloop: OWIn DQ, 4, [count_remain] ' Check for still busy converting
IF count_remain = 0 Then waitloop
OWOut DQ, 1, [$CC, $BE] ' Read the temperature
OWIn DQ, 0, [temperature.LOWBYTE, temperature.HIGHBYTE, Skip 4, count_remain, count_per_c]
' Calculate temperature in degrees C to 2 decimal places (not valid for negative temperature)
temperature = (((temperature >> 1) * 100) - 25) + (((count_per_c - count_remain) * 100) / count_per_c)
LCDOut $fe, 1, DEC (temperature / 100), ".", DEC1 temperature, "C Boiler"
OWOut DP, 1, [$CC, $44] ' Start temperature conversion
waitloop2: OWIn DP, 4, [count_rempan] ' Check for still busy converting
IF count_rempan = 0 Then waitloop2
OWOut DP, 1, [$CC, $BE] ' Read the temperature
OWIn DP, 0, [temperapanel.LOWBYTE, temperapanel.HIGHBYTE, Skip 4, count_rempan, count_per_cpan]
' Calculate temperature in degrees C to 2 decimal places (not valid for negative temperature)
temperapanel = (((temperapanel >> 1) * 100) - 25) + (((count_per_cpan - count_rempan) * 100) / count_per_cpan)
LCDOut $fe, $c0, DEC (temperapanel / 100), ".", DEC1 temperapanel, "C Panel"
Pause 3000 ' Display about once every 3 seconds
IF temperapanel < 1800 Then mainloop 'Less than 18°C? Pump stays off
IF temperapanel > (temperature + delta) Then 'Checks T diff. for the pump to start (default 7°C)
High PORTC.4 'Start pump
EndIF
IF PORTC.4 Then 'Check for PORTC pin 4 high
LCDOut $fe,$c0+4, " h2o PUMPING" 'It's high so pump is on
EndIF
IF temperapanel < (temperature +300) Then 'Checks if T difference < 3°C
Low PORTC.4 'Stop pump
EndIF
Pause 3000 ' Refresh time =~3 seconds
GoTo mainloop ' Do it forever
End
pressed: Pause 30 'debounce
IF PORTA.3 = 0 Then setdelta 'IF STILL PRESSED GO TO SETDELTA
setdelta: For delta = 700 TO 2000 STEP 100 ' STEP SIZE 1°C
LCDOut $fe, 1, "Delta ", delta 'CLEAR LCD AND DISPLAY DELTA VALUE
Pause 3000
IF PORTA.3 = 1 Then mainloop 'if not pressed go to mainloop
Next delta
GoTo setdelta
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